The invention relates generally to an adhesive-fixed body which can contain an electronic apparatus, such as a watch and more particularly to a body or watch having high waterproof, moisture proof, water resistance, moisture resistance, durability and/or shock resistance properties.
Conventional waterproof watches generally have a structure in which a synthetic resin gasket or packing is press-fit to the engagement portion between a watch case body and a transparent cover glass (watch crystal) to fix both members and ensure a waterproof coupling. However, this method increases the thickness of the gasket needed, to some extent, in order to obtain sufficient sealing performance, and requires the watch case body and the transparent glass (crystal) which supports the gasket, to have predetermined rigidity. Therefore, the dimensions of the watch in the thickness and plane directions are inevitably increased. Also, it is necessary to prepare gaskets of varying shapes corresponding to each watch type, which complicates management of parts and the assembly and repair process.
An assembly technique has been proposed in which parts of a watch are bonded and fixed directly with an adhesive without using a gasket. Japanese Examined Patent Publication No. 7-98674 discloses a structure in which a watch case body and transparent glass are bonded and fixed with a highly waterproof and durable adhesive. However, a conventional watch having the structure in which both members are bonded and fixed with adhesive has an inadequacy, such as being insufficiently waterproof, when the water pressure increases to 5 atm or more. Also, such a structure can have durability problems due to dissolution of the adhesive layer from long term water exposure. The adhesive disclosed in the above Japanese Patent Publication No. 7-98674 has less problems with deterioration after exposure to water, as compared with previous adhesives, but undesireable deterioration can occur when the adhesive is immersed in hot water for a long period of time. Therefore, the adhesive cannot be used for many applications in which there are opportunities for long term contact with water, such as sea bathing, bathing, fishing, kitchen work, etc.
Bodies fixed with many conventional ultraviolet curable adhesives and other epoxy adhesives can have a problem in that curing proceeds and brittleness increases with time. This can deteriorate shock resistance. If the shock resistance deteriorates due to an increase in brittleness of the adhesive layer, such as, when a watch is used in an outdoor sport, the adhesive layer can become cracked when shock is applied to the watch. This can eliminate the waterproof effect, and cause peeling or separation between adhered parts. Therefore, in the case of a waterproof watch, deterioration in shock resistance can be a fatal defect.
Accordingly, is it desirable to provide an adhesive-fixed body, such as a watch, which overcomes inadequacies of the prior art.